accel/amdxdna: reject a command chain that carries no commands

A chain whose command_count is zero passes the payload length check,
because struct_size(payload, data, 0) is just the header. The fill loop
then does not run, so offset stays zero and the request is submitted with
a zero-length buffer.

On firmware without AIE2_NPU_COMMAND that ends at the opcode check, since
op is still ERT_INVALID_CMD and aie2_get_chain_msg_op() answers
MSG_OP_MAX_OPCODE. aie2_get_npu_chain_msg_op() answers
MSG_OP_CHAIN_EXEC_NPU whatever it is given, so there the submission
continues to drm_clflush_virt_range(cmd_buf, 0), which reads the byte
before the buffer and faults on the vmap guard page. EXEC_CMD is
reachable by any process that can open the render node.

Reject the request instead.

Fixes: 8ed8b0239617 ("accel/amdxdna: Add debug prints for command submission")
Signed-off-by: Taimuraz Kaitmazov <taimuraz@kaitmazov.com>
Reviewed-by: Lizhi Hou <lizhi.hou@amd.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260818000019.369366-1-taimuraz@kaitmazov.com

0 files changed, 0 insertions, 0 deletions